Monday, December 31, 2007


The following observations taken here at the house - north end of Country Club about a half mile south of the Rillito Wash - document what was an unusual early December rainy period that was followed by a very cold last half of December. Note that the part of Tucson we live in is considerably lower in elevation than the official NWS observation site at the airport on the far south side of the city. On clear and calm nights low temperatures here at the house are routinely at least 8 to 10 degrees F colder than the "official" readings at the airport. I do not record maximum temperatures here at the house because I have never been able to screen my max/min thermometer adequately to avoid contamination by daytime solar heating.

December 2007 Precipitation (I read my gauge at about 7 am each morning so that some rainfall may have actually occurred after midnight and technically be for the next day):

Dec. 1 - 1.84" No thunderstorms observed at house
Dec. 2 - 0.05"
Dec 7 & 8 - 0.62" We were out of town from Friday afternoon until Sat. evening.
Dec. 9 - 0.04"
Dec. 10 - 0.23" Strong thunderstorms occurred late afternoon on Monday and pea size hail fell here at the house at dusk.
Dec. 11 - 0.40"
Dec. 12 - very dense fog until about 11 am in the morning.
Dec. 21 - 0.05" In addition to the light rain there was a brief burst of snow pellets here at the house about 9:30 am. Weather broadcasts erroneously referred to the occurrence of sleet around town.

Total December precipitation: 3.23 inches

Minimum temperatures:

24 days had lows of 39F or colder
16 days had lows of 29F or colder
3 days had lows of 19F or colder

An extended period of very cold morning lows (at least for here in Tucson) began the morning of the 15th - as per:

15th - 24F The first hard freeze with very heavy frost here at house.
16th - 24F
17th - 29F
18th - 29F
19th - 29F
20th - 27F
21st - 36F
22nd - 21F
23rd - 19F
24th - 24F
25th - 26F
26th - 18F
27th - 23F
28th - 19F
29th - 22F
30th - 24F
31st - 24F

The extended period of cold temperatures caused fairly heavy plant damage here at house, and I hauled out about 100 lbs of broken and fallen cacti arms this morning.

My summary of the entire year, highlighting significant weather events, will follow by the end of the week.

Happy New Years to all!